Non-phytate phosphorus requirements of egg laying pullets from 0 to 3 weeks of age and carryover effects of phosphorus deficiency at 6, 9, 12, and 18 weeks of age

Abstract

The objectives were to determine the non-phytate phosphorus ( nPP ) requirement in 0 to 3-wk-old laying hen pullets using body weight ( BW ), mortality corrected feed conversion ratio ( FCRm ), tibia ash expressed as weight ( TAW ) and percentage ( TAP ), and total body bone mineral content ( BMC ) and to understand the longer term effects of early phosphorus deficiency on pullets over time. Hy-Line W36 pullets were distributed across 42 cages resulting in 7 dietary treatments (0.15, 0.22, 0.29, 0.36, 0.43, 0.49, and 0.53% nPP and 1.0% Calcium) fed across 6 replicate cages of 30 chicks. After 3 wk, all birds were switched to common corn-soybean meal diets that contained 0.49, 0.48, 0.45, 0.48% nPP and 1.0, 1.0, 1.0, 2.5% Ca from 3–6, 6-12, 12–15, 15–18, respectively. Pullets were euthanized at 3, 6, 9, 12, and 18 wk of age for BMC and tibia ash determination. Linear and quadratic broken-lines were used to estimate nPP requirements of 0 to 3-wk-old pullets. The nPP requirement was 0.31% nPP for BW; 0.27% nPP for FCRm; 0.31% for TAP; 0.31% for TAW; 0.32% for BMC using linear broken line analysis. Low concentrations of dietary nPP fed over the 0 to 3 wk period reduced BW at 6 wk ( P ≤ 0.05), but after 9 wk no response criteria were different among the dietary nPP treatments ( P > 0.05). These data indicate that the nPP requirement for pullets from 0 to 3 wk is between 0.27 and 0.32% nPP dependent on response criteria used, and that there are few to no long-term effects of low phosphorus feeding when pullets are provided an adequate nPP diet over time.